Motor-control system.



W. C. KORTHALS-ALTES.

MOTOR CONTROL SYSTEM.

APPLICATION FILED MAR. 16. l9l8.

1 ,27 9 360. Patented Sept. 17,1918.

lnve ntorr Willem CKor-thals-v ltes,

lb9 I Hiso ttor-neg.

m: Nosms PETERS m" womumm, WASNING 10M, :1. cv

I UNITED STATES OFFTCE.

WILLEM C. KORTHALS-ALTES, OESCHENECTADY, NEVT YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A GOBPQRATION NEW YORK.

MOTOR-CONTROL SYSTEM.

To all whom it may concern:

Be it known that I, WILLEM C. Kon- THALs-ALTns, a subject of the Queenof the Netherlands, residing'at Schenectady, county of Schenectady,State of New York, have invented certain new and useful Improvements inMotor-Control Systems, of which the following is a specification.

My invention relates to the control of electricmotorsand has for itsobject the provision of improved means whereby an elec tric motor may bestarted, stopped and generally controlled in a reliable, simple andeflicient manner;

My invention relates more specifically to the control of electric motorswherein the speed of the motor is varied by a motor driven controllerunder the control of manually operated switches. One particularapplication to which my invention is well adapted is that of analternating current commutator motor in which the speed is varied byshifting the brushes. It is desirable that these motors be controlled byman ually operated switches such, for instance, as push buttons, one ofwhich is provided to start the motor, one to speed it up and another toslow down the motor It is also desirable that when the motor is startedthe control shall be in a condition to give normal speed, that is, inthe case of a brush shifting motor, for instance, the brushes shall bein their neutral position. It is also impor tant that the motor shall bedisconnected from the line when the speed is below a predetermined valueso as to prevent it being stalled by an overload and left standing withthe power on the motor. 1

In carrying out my invention, I provide means whereby the above objectsare obtained in a very simple manner. I use a pilot motor for varyingthe speed of the main motor and provide means whereby the pilot motor ispromptly brought to rest by a dynamic braking action, thereby renderingthe controller accurate andjp'ositive. In the accompanying drawingillustrating my invention Figure 1 is a diagrammatic view showing oneform in which my invention may be applied to a brush shifting motor, andFig. Q'shows a similar control embodying certain additional features.

Referringfirst to Fig. 1, M represents the main'motor to be controlled.For purposes of illustration I have shown this motor as Specification ofLetters Patent.

Patented Sept. 1'7, 1918.

Serial No. 222,804.

of the brush shifting type, the stator being indicated at S and therotor at R. I have simply shown the parts in a conventional way, thebrush rigging being really shown as a ring 10 carrying brushes 11, thering being adapted to be rotated through the rod 12. For shifting thebrushes I provide a pilot motor m connected to drive a circuitcontroller C through a belt 13. Attached to the moving element of thecontroller C is an arm 14; which is pivoted to the rod 12, so that asthe pilot motor rotates and turns the controller C, it will also shiftthe brushes of the motor M. The pilot motor m is made reversible byproviding two field windings F and F, one of which is energized inseries with the motor armature for each direction of lo tation. Therotating element of the controller C, which is pivoted at 15, comprisesthree contact arms 16, 17 and 18. The arm 16 engages segments 19 and 20and the arm 18 engages segments 21 and 22. In the neutral position ofthe controller, which is the position shown in the drawing, the contactarm 17 engages only contact ring 23 but when the controller is moved ineither direction to near its limit, the arm will engage either thesegments 20 or 22, depending upon the direction in which the controlleris moved. The electromagnetic switch 24, I have shown as of thetriple-pole type, since the motor is a three-phase motor connected tothree-phase mains. This switch is adapted to close the stator circuit ofthe motor and is also provided with an interlock contact for purposeshereinafter described. I also provide a switch 26 which is only closedwhen the main motor is at or above a predetermined speed. For purposesof illustration I have shown this switch as being operated by a fly-ballgovernor 27. Four push button switches are provided, one 2. normallyopen switch for starting the motor, one for operating the pilot motor toslow down the main motor, a third switch for operating the pilot motorto speed up the main motor and a fourth normally closed switch forstopping the main motor.

As thus constructed and arranged, the

- operation of my control system is as fol lows: To start the motor thepush button switch marked Start is closed thereby energizing the windingof the line switch 24:, from main 7), through the contacts of the switchand the contacts of the stop start button.

push button back to line 0. W'henthe switch 2% closes it energizes thestator winding of the motor and closes interlocking contact 25:

This switch may, therefore, be used for jogging the motor. V7 hen themotor reaches asuitable speed the switch 26 is closed and a maintainingcircuit for the switch 2% is made through the interlock 25, switch 26and the stop button, this circuit being independent of the The operatormay now, therefore, release the start button, and the motor will run atits normal speed; If, however, it is desired to slow down the motor theslow button is pressed, thereby ene'rgizing the pilot motor asfollowszifrom thelline 0 through the contacts of the slow button,segment 21, contact arm 18, segment field winding?" and armature of themotor-m to line b. 'The motor will. therefore, now rotate the controllerC. and also shift the brushes of the motor Min a di: rection to reduceits speed. If the operator maintains the slow button closed, the conrin23 contact arm 17. se ment 20 field winding F and armature of the pilotmotor to line b. Thiscircuit will not, however,

be com lcted until the line switch E L-o ens the object of :thisarrangement :being to move the controller back to neutral positionwhenever-the line switch opens, so that the main motor will always startwith the brushes in the neutral position. if the fast button pressed,the field winding F will be'energized to energize the pilot motor foroperation in adirection to increase the speed of the main motor, andupon the release oft-the push button the circuit will be made whichsvillbe completed whenthe line switch opens and turn the controller bacl: toneutral. If the motor should become overloaded so as to mate- C backtocneutral At anytime, however,

the motor may be stopped by pressing the stop button.

In starting, therefore, theoperator must keep the start button closeduntil the motor arrives at the V predetermined speed.

Likewise,

In Fig, Q I h aVe shown a similar arrange I ment in which, however,there are some ad ditional features prominent among which is the dynamicbraking of the pilot motor;

In this case instead of controlling the pilot niotor through thecontroller C directly, I

control it through electromagnetic'switohes. lVhen the start button inthis form of my invention is closeda circuit is established from theline a throughthewinding of the line switch 24:, through contacts of thestart.button,-contactslof the stop button, and back to line as before.down the motor the slow buttonis pressed and a circuit established fromthe line b,con-

ductor 28 through the contacts of the slow button, segments 21' and 22to the winding of the electromagnetic switch 8, and back to line. Thisswitch's is provided" with a contact 30, so that when the switch closes,a'

second switch 8 will be closed, the energizing circuit being from lineathrough the winding of the switch s',tlirough the contact 30 of switch8, thence through contact 31 of switch 7" and back to line. The switchess and s bein now both closed, the pilot motor m will e energized fromthe linea.

through the armature of the motor, through the field winding F, thencethrough the. con tact 29 of switch 8, and back to line. 7 The motor willnow operate in a direction to shift 18 will leave the segment 21, thecontact 17' in the meantime moving onto the segment 20. Thepilot motorwill now be deenen' V gized and the controller C will be in a positionto reverse the motor and return the controller to its neutral positionin case the contactor 24" opens, all'as desoribedin connec-e t1on withFig. 1. When the operator re-' leases the slow button, or when thecontact 18 passes off segment 21 adynamic brake ing circuit isestablished which stops the pilot motor. It will be noted that when theswitch 5 closes, it makes a maintaining circuit. for its windingthroughcontact 32 and contact 31 of switch f, so that the'opening of theswitch 8 does not cause the opening;

of the switch 8. A dynamic braking circuit ,of the motor m will,therefore, be completed from the left hand brush of the pilotmotorthrough the contact 33 on therswitch 7, con- To slow tact 29 :on theswitch s,contact 34 ofswitchj s which is now up, field ;WiIldii1g' F and7' back .to the motorarmature. Thisrdynamid braking circuitwill-gbringthe motor to rest];

promptly. If, onfthe other hand, itis desired to speed up the motor thefast button is pressed, thereby establishing the cir-x;

cuit'thro-ugh the line 1), "segments l9 -and 20 to winding of switch fand'back to line. I

; The switch 7" will, therefore, close and complete a circuit for thepilot motor from' the linea through the motor armature, through thefield F and through thecontact 33 of switch 7 back to line. The pilotmotor will now'operate as above described to shift the brushes and turnthe controller to finally stop the pilot motor and also make theconnections for returning'the pilot motor to neutral position upon theopening of the line contact at. Upon the release of the fast button, thedynamic braking circuit will be established from the left hand brush ofthe pilot motor, through contacts 33 of switch 7, through contact 29 ofswitch 8, through contact 34 of switch 8, which is now open, and throughthe field winding F to the motor armature. It will be noted that in thedynamic braking in one direction the switch 8 is opened, and in theother direction it is closed, thereby simplifying the dynamic brakingconnections. It will also be noted that the motor m is at all timesconnected to line but during stopping and while the motor is at rest,this connection is through the high resistance r to initiate the selfexcitation but the current flowing into the motor will be negligible. Aspeed controlled switch 26 is also employed in the same way and for thesame purpose as in Fig. 1 and need not, therefore, be further described.

While I have described my invention as embodied in concrete form and asoperating in a specific manner in accordance with the provision of thepatent statutes, it should be understood that I do not limit myinvention thereto, since various modifications thereof will suggestthemselves to those skilled in the art, without departing from thespirit of my invention the scope of which is set forth in the annexedclaims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. The combination with an electric motor of means for controlling thesame comprising a controller, a pilot motor for operating the same intwo directions from a neutral position to either accelerate or slow downthe motor. manually operated normally inoperative switches, one forvarying the speed of the motor in each direction, and

means whereby when the pilot motor has varied its speed a predeterminedamount it is automatically stopped by dynamic brakmg.

2. The combination with an electric motor of means for controlling thesame comprising a controller, a pilot motor for operating the same intwo directions from a neutral position to either accelerate or slow downthe motor, a manually operated switch for starting the motorindependently of the controller, and means whereby when the motor speedincreases to a predetermined value the said manually operated switch isrendered ineffective to control the motor.

3. The-combination with an electric motor of means for controlling thesame comprisinga controller, a pilot motor for operating thesame in twodirections from a neutral position to either accelerate or slow down themotor, a manually operated switch for start ing the motorindependentlyof the controlle'r, and means whereby when the motor speed decreases toa predetermined value the motor is stopped independently of thc motoroperated switch.

4. The combination with an electric motor, of means for controlling thesame comprising a controller, a pilot motor for operating the same intwo directions from a neutral position to accelerate and slow down themotor, manually operated normally inoperative switches, one for varyingthe speed of the motor in each direction, means whereby upon the releaseof either of said speed varying switches from operative positionconnections are established for returning the controller to neutralposition upon the opening of the motor circuit, and a dynamic brakingcircuit for the pilot motor established upon the release of either ofsaid switches.

5. The combination with an electric motor of means for controlling thesame comprising a controller automatically operated in two directionsfrom a neutral position to accelerate and slow down the motorrespectively, a manually operated switch normally in inoperativeposition for starting the motor, means whereby when the motor reaches apredetermined speed the motor circuit is held closed independently ofsaid switch, manually operated normally inoperative switches, one forvarying the speed of the motor in each direction and means whereby uponthe release of either of said speed varying switches from operativeposition, connections are established for returning the controller toneutral position upon the open ing of the circuit of the motor or thereduction of its speed-below said predetermined speed.

6. The combination with an electric motor of means for varying its speedcomprising a pilot motor connected to shift the brushes of said motor intwo directions from neutral, a manually operated switch for starting themotor independently of the controller, manually operated normallyinoperative switches, one for efiecting the move ment of the brushes ineach direction to accelerate and slow down the motor respectively, andmeans whereby upon the release of either of said speed varying switchesfrom operative position connections are established for returning thecontroller to neutral position upon the opening of the motor circuit. V

7. The combination with an electric motor of means for controlling thesame comprising a controller automatically operated 5 ler, manuallyoperated switches, one for l efi'ecting the operation of the controllerthrough a predetermined range in each direction and means whereby uponthe release ofeither of said switches from.-operative positionconnections are-established for re- 10 turning the controller to neutralposition 7 upon the opening of the motor circuit. V A In witnesswhereof, I have hereunto set my hand this 14th day of March, 1918.

' Wi LE c. KoRTHAL s-ALTEs.

Copies of this patent may be obtained for five cents each; by addressingthe Commissioner of'Patents,

Washington, D 0.

